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The complex [Cu2(μ-L)2]. DMF (L = 2, 2'-[1-(2, 4, 6-trichlorophenyl)-1H-1, 2, 4-triazole-3, 5-diyl] diphenolate) has been prepared and its structure determined. The two CuII ions are four-coordinated in a planar structure, with the DMF molecule wrapped in the 'wings' of ligand L. Hirshfeld surface and fingerprint plots reveal that the complex structure is stabilised mainly by H···H, C-H ... Cl, C-H···π,π···π and lone-pair···π (C-Cl) intermolecular interactions. [ABSTRACT FROM AUTHOR]

The complex [N(CH3)4]3[Mn3Zn2(3,5-dibromosalox)3O(N3)6Cl2] has been synthesised and characterised. It crystallises as two independent molecules and exhibits a planar [MnIII3-(μ3-oxo)] core as well as μ2-η1:η1-azide bridging geometry. DNA binding studies show that the complex binds with DNA through intercalation. [ABSTRACT FROM AUTHOR]

Two novel bimetallic coordination polymers, [Cu(en)2][Mn(dca)4] (1) and [Cu(pn)2][Mn(dca)4] (2) (en, ethylenediamine; pn, 1,3-diaminopropane; dca, dicyanamide N(CN)2−), have been synthesized and characterized. Both of them consist of Mn&z.sbnd;dca anionic chains and chelate cations of copper. 1 has a sheet like architecture built by the [Cu(en)2]2+ cations and the homoleptic trans-[Mn(dca)4 2−]n chains. 2 shows unusual 3-D threefold interpenetrating diamond-like structure constructed by [Cu(pn)2]2+ cations and the homoleptic cis-[Mn(dca)4 2−]n chains. The magnetic susceptibilities obey the Curie–Weiss law with weak antiferromagnetic interactions. [Copyright &y& Elsevier]

The title compound, [Cu(C2N3)2(C12H8N2)] n, has a sheet-like structure, built by [Cu(phen)(dca)2] n (phen is 1,10-phenanthroline and dca is dicyan­amide) chains which are interconnected by secondary long Cu-N bonds between the chains. The Cu2+ ion is in a distorted tetragonal bipyramidal (5 + 1) coordination environment. The sheets stack into the three-dimensional crystal structure through aromatic interactions between the coordinated phen ligands of adjacent sheets. [ABSTRACT FROM AUTHOR]

Owing to the critical roles it plays for both structure and functionality, hydrogen bonding has high hopes for the orientated applications in hydrogen‐bonded organic frameworks (HOFs). Here in this work, a hydrogen‐bonding strategy is performed for adjusting the structure and functionality of a heme‐like ligand meso‐tetra(carboxy‐phenyl)‐porphyrin (TCPP) with co‐former 1,3‐di(4‐pyridyl) propane (1,3‐DPP). A 3D dynamic HOF TCPP‐1,3–DPP, with permanent porosity is obtained. For this HOF, the two components form novel robust 1D porous stripes, with the 1,3‐DPP molecules acting as the lining for the pores that are confined within the region between adjacent carboxyphenyl moieties of TCPP. This confinement has tuned the affinities of TCPP from hydrophobic into hydrophilic. Interestingly, the 1D stripes are further stacked by weak π...π interactions into a 3D framework, the latter is highly dynamic with 1D stripes sliding back and forth, upon pressurized and water adsorption in the solid‐state under ambient conditions, respectively. The activated TCPP‐1,3–DPP has a Brunauer–Emmett–Teller surface area of 258 m2 g−1, and shows a maximum adsorption capacity about 9.8% for water during the adsorption–desorption cycles, demonstrating a promising candidate for the real‐world application in effective dehydration of industrial gases under ambient conditions. A 3D dynamic hydrogen‐bonded organic framework TCPP‐1,3–DPP, which is composed of 1D porous stripes, shows permanent porosity and highly affinity to water. The activated species exhibit a maximum adsorption capacity about 9.8% for water during the adsorption–desorption cycles, demonstrating a promise for the real‐world application in effective dehydration of industrial gas under ambient condition. [ABSTRACT FROM AUTHOR]

Co-crystallization of 4-hydroxyisophthalic acid (4-HIPA) with 2-methylpyrazine (MP), 2,3-dimethylpyrazine (DMP), and 2,3,5,6-tetramethylpyrazine (TMP) has been performed, resulting in the formation of three co-crystals 1 (MP:2(4-HIPA)), 2 (DMP:2(4-HIPA)), and 3 (TMP:2(4-HIPA)), respectively. The co-crystals were analyzed using single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis (TGA), fluorescence spectroscopy, and UV–vis spectroscopy. Hirshfeld surface analysis revealed that the proportion of O–H⋯N interactions in the co-crystals decreased with increasing number of methyl groups on the pyrazine derivative. In comparison with 4-HIPA, the maximum absorption peaks in the UV–vis absorption spectra of co-crystals 1 – 3 exhibited a red shift, which was caused by the presence of the corresponding pyrazine derivative in each case. As the number of methyl groups on the pyrazine derivatives increased, a weak blue shift was observed in UV–vis spectrum (Fig. 5). The fluorescence emission spectra peaks of co-crystal 1–3 were nearly at same position, 440 nm for solution state, 396 nm for solid state, irrespective of the number of methyl groups. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two new complexes from 6-methylnicotinic acid (6-MNA) have been presented. [•] Influences of metals on 6-MNA through Hirsheld surfaces have been investigated. [•] Intermolecular interactions of complexes have been quantificationally visualized. [ABSTRACT FROM AUTHOR]

Highlights: [•] The fourth CuII–azido-pyrazine complex has been synthesised and characterized. [•] The crystal structure display novel 3D-42.63.8-topology with 2D honeycomb layer. [•] The complex exhibit strong antiferromagnetic coupling. [Copyright &y& Elsevier]

• Multicomponent crystallization was used to improve the solubility of bromhexine. • A new bromhexine crystal and its fumarate salt crystal have been synthesized. • The crystal structure and Hirshfeld analyses of the two crystals were investigated. • The multicomponent crystal shows higher thermal stability and improved solubility. Bromhexine is an expectorant drug repurposing as a TMPRSS2 inhibitor, which has also been proposed for potential treatment in COVID-19 infection. Multicomponent crystal strategy has been applied in bromhexine to improve its poor solubility, which limits its bioavailability and efficacy. A new bromhexine crystal and its fumarate salt crystal have been successfully obtained by slow evaporation technique. Both compounds have been characterized by X-ray single-crystal diffraction, TGA and FT-IR spectroscopy. Hirshfeld surface analysis has been carried out to further quantify the patterns of intermolecular interactions. Compared with bromhexine, the multicomponent crystal with pharmaceutically acceptable conformer of fumaric acid shows improved thermal stability and solubility in water. [ABSTRACT FROM AUTHOR]

Cocrystal modification strategy has been applied to 3,5-dichlorosalicylic acid (DCA) through the addition of various liquid pyrazine derivatives: 2,3-dimethylpyrazine (2,3-DMP); 2,5-dimethylpyrazine (2,5-DMP); and 2,3,5-trimethylpyrazine (TMP). Three new cocrystals (2,3-DMP-DCA = 1:2 for 1; 2,5-DMP-DCA = 1:2 for 2; and TMP-DCA = 1:1 for 3) have been obtained, all of which were characterized by X-ray diffraction analysis, infrared spectroscopy, thermogravimetric analyses and UV–Vis spectroscopy. The Hirshfeld surface analysis has been performed to illustrate the intermolecular interactions. The results revealed that hydrogen bonding and other weaker interactions such as halogen bonding contacts and π···π stacking participated in a cooperative way to stabilize the supramolecular structures and different methyl substitutions changed the bonding mode and intermolecular force of pyrazine derivative cocrystals. Thermodynamic results showed that the stability of liquid pyrazine spices can be improved and the decomposition temperature for cocrystal 3 is higher than the other cocrystals. This work provides an approach to solidification of liquid pyrazine spices for more applications. [ABSTRACT FROM AUTHOR]

Precise revealing the mechanisms of excited‐state intermolecular proton transfer (ESPT) and the corresponding geometrical relaxation upon photoexcitation and photoionization remains a formidable challenge. In this work, the compound (E)‐4‐(((4H‐1,2,4‐triazol‐4‐yl)imino)methyl)‐2,6‐dimethoxyphenol (TIMDP) adopting a D‐π‐A molecular architecture featuring a significant intramolecular charge transfer (ICT) effect has been designed. With the presence of perchloric acid (35 %), TIMDP can be dissolved through the formation of a HClO4–H2O–OH(TIMDP)–N(TIMDP) hydrogen‐bonding bridge. At the ground state, the ICT effect is dominant, giving birth to crystals of TIMDP. Upon external stimuli (e.g. UV light irradiation, electro field), the excited state is achieved, which weakens the ICT effect, and significantly promotes the ESPT effect along the hydrogen‐bonding bridge, resulting in crystals of [HTIMDP]+⋅[H2O]⋅[ClO4]−. As a consequence, the mechanisms of the ESPT can be investigated, which distorted the D‐π‐A molecular architecture, tuned the emission color with the largest Stokes shift of 242 nm, and finally, high photoluminescence quantum yields (12 %) and long fluorescence lifetimes (8.6 μs) have achieved. These results not only provide new insight into ESPT mechanisms, but also open a new avenue for the design of efficient ESPT emitters. [ABSTRACT FROM AUTHOR]

Abstract A new complex [Fe(CN) 2 (bipy-NH 2) 2 ] (2 , bipy-NH 2 = 4, 4′-diamino-2, 2′-bipyridine), which was designed through ligand exchange strategy, has been prepared and characterized. The magnetism properties of 2 have been tuned through protonate the amino groups on bipy-NH 2 ligand with HCl in stoichiometric ratio 2 :HCl below 1:1. Further increase the ratio exceed 1:1 has induced the distortion of the bipy-ammonium moieties in bipy-NH 3 2+ cation, with the dihedral angle involving the mean plane change from 0° to 37°. This distortion, on the one hand, responsible for the decomposition of 2 , on the other hand, take charge the break of the precursor complex 1 ([Fe(H 2 Bpz 2) 2 (bipy-NH 2)]) (pz = pyrazolyl) upon protonation. Graphical abstract Tuning the magnetism properties of a new complex [Fe(CN) 2 (bipy-NH 2) 2 ] (2) through protonation of the ligand bipy-NH 2 with HCl have been investigated with stoichiometric ratio of 2 :HCl below 1:1. While once the ratio larger than 1:1, ligand bipy-NH 2 has distorted with the mean plane of bipy-ammonium moieties to form a dihedral angle large to be 37°. Unlabelled Image Highlights • The protonation of a Fe(II) complex has been investigated. • The mechanism of protonation induced decomposition of Fe(II) complex has been proposed. • The mean plane of bipy-ammonium moieties has been distorted with dihedral angle large to be 37°. [ABSTRACT FROM AUTHOR]

Abstract Cisplatin is a highly effective antitumor drug, which can kill cancer cells by crossing-linking DNA and inhibiting transcription, but this process is limited by the combination of cisplatin and many endogenous nucleophiles, such as glutathione (GSH). Thus, when cisplatin enter cells, it is potentially vulnerable to cytoplasmic inactivation by GSH. To settle this bottleneck, we designed and synthesized a probe compound (Probe 1) and fabricated pH-responsed cisplatin, Probe 1-loaded lipid-polymer hybrid NanoParticles (CPNPs) using a single-step sonication method. Probe 1 can specifically bind to GSH, thus avoiding the combination of GSH and cisplatin, and enhancing the pharmacological activity of cisplatin. In vitro studies have suggested CPNPs, compared with cisplatin, loaded lipid-polymer hybrid NanoParticles CNPs (Not contain Probe 1), could efficiently kill MCF-7 human breast cancer cells and A549 human nonsmall lung cancer cell. Hence, the CPNPs provided a new idea for treating cancer. Highlights • First, Probe 1-loaded lipid-polymer hybrid nanoparticles (CPNPs) uses a single-step sonication method. • Second,it can avoid the combination of GSH and cisplatin, and enhance the therapy activity of cisplatin. • Third, it exhibits great potential in the therapy ability of cisplatin and provide a new ideal for tumor therapy. [ABSTRACT FROM AUTHOR]

A new complex of the title system ([2(H 3 O + )·18-crown-6]·2[BF 4 − ]), which was induced by external magnetic field, has been prepared and characterized. When compared with other two members of the same system, the proton transfer induced by magnetic field from HBF 4 to H 2 O has leads to the co-plane of six oxygen atoms in the crown and stronger H F and O F intermolecular interactions, which can be attributed to the closer contacts between 18-crown-6, oxonium ion H 3 O + and counterion BF 4 − . In addition, a compression effect of crystals stacking has been observed. These results are of importance for the evaluation the effect of magnetic field on the host–guest systems. [ABSTRACT FROM AUTHOR]

In this work, two new single crystals of copper-tetraphenylporphine (Cu-TPP) (crystals 2 and 3), which were induced by external magnetic fields with strengths of 0.5 and 0.8 T, respectively, have been prepared and characterized by single-crystal X-ray diffraction and Hirshfeld surface analysis. Compared with the original Cu-TPP (crystal 1), crystals 2 and 3 exhibit significant differences in their unit cell parameters, crystalline stacking styles and intermolecular interactions, resulting in a “compressed” crystal packing. Here, the number of closer interactions (H…H, C…H/H…C) increased with the magnetic field strength, accompanied by a decrease in the number of π…π (C…C) interactions as a sacrifice. On considering the results of our previous work, the results here suggest that a magnetic field has a different influence on the crystallization process of mono-component and multi-component materials, which will certainly provide some suggestions for the design of crystallization strategies for other materials with the presence of an external magnetic field. [ABSTRACT FROM AUTHOR]

Three salts: 3-amino-1,2,4-triazolinium (1+) hydrogen oxalate ( 1 ), 3-amino-1,2, 4-triazolinium (1+) hydrogen malonate ( 2 ), 3-amino-1,2,4-triazolinium (1+) hydrogen succinate ( 3 ) and one co-crystal: 3-amino-1,2,4-triazole-adipic acid ( 4 ) have been prepared and characterized by differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), IR, Raman, and single-crystal X-ray diffraction. Wherein, supramolecular motif in salts 1 , 3 and co-crystal 4 were dominant by triazole-acid and amino-acid heterosynthon, while salt 2 dominant by amino-triazole homosynthon in addition to triazole-acid heterosynthon, which attribute to the intermolecular hydrogen interactions within hydrogen malonate anion. These results have a close relationship with the ΔpKa between 3-ATZ and alkyl acids, we found that the ΔpKa is grate than 6.9, the formation of salt will be expected, while the formation of co-crystal usually with the ΔpKa less than 6.75. It is interesting that salts 2 and 3 show the phenomenon of proton transfer after melt, which lead to the stepwise sublimation of the two components. The differences between salts and co-crystal were also revealed by the solid-state vibrational spectroscopy (IR and Raman), Hirshfeld surface analysis and UV spectra. [ABSTRACT FROM AUTHOR]

Two zinc (II) pseudo-halide complexes [Zn( L 1 )(N 3 ) 2 ] n ( 1 L 1 : 1,2-diaminocyclohexane) and Zn( L 2 ) 2 (N 3 ) 2 ( 2 L 2 : 4,5-dimethy-2-(pyridine-2-yl) imidazole) have been synthesized and characterized. Single-crystal X-ray structural analysis revealed that the central Zn II atoms in 1 displays distorted trigonal bipyramidal arrangement with a 1D chain structure bridged by N 3 − anions, while in 2 , the central Zn II atoms incorporating with two bidentate L 2 ligands, and adopts an octahedral geometry and shows a “butterfly” coordination framework. Structural analysis demonstrated that the organic ligands play an important role in determining the resultant structure. In addition, both complexes were further characterized by thermal stability properties and Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

Four new complexes based on the 4-(4-carboxyphenyl)-1,2,4-triazole (Hcpt) ligand, {[Co(cpt) 2 (H 2 O) 4 ]·H 2 O}( 1 ), {[Cr(cpt) 2 (H 2 O) 4 ]·10H 2 O}( 2 ), {[Fe(cpt) 2 (H 2 O) 4 ]·10H 2 O}( 3 ), {[Zn(cpt) 2 (H 2 O) 2 ]}( 4 ) have been synthesized and characterized by elemental analysis, single crystal X-ray diffraction and TGA. For complexes 1 , 2 , and 3 , they almost have the same coordination mode that only one nitrogen atom of triazole are involved in the coordination, while in the complex 4 , only the group COO − participates in the coordination. In the crystal structure of 1 , each structural unit[Co(cpt) 2 (H 2 O) 4 ] is linked to another by hydrogen bonding formed by the lattice water molecules, thus forming a one-dimensional chain structure; In the crystal structure of 2 or 3, each structural unit[Cr(cpt) 2 (H 2 O) 4 ] or [Fe(cpt) 2 (H 2 O) 4 ] forms a two-dimensional layered structure by intermolecular hydrogen bonds from the coordinated water molecule and the group COO − . The results of thermogravimetric analysis show that the loss of lattice water and coordinated water molecules in 1 , 2 and 3 is below 120 °C, while the loss of coordinated water molecules in 4 is in the temperature range of 190–260 °C. Hirshfeld surface shows that the N H⋯O hydrogen bonding interaction plays a significant role towards the conformation of the basic structure of these complexes. [ABSTRACT FROM AUTHOR]

In order to determine the effect of halogen bonding on supramolecular assemblies and photophysical properties of diaryl oxalates, diaryl oxalate itself and its derivatives with fluorine, chlorine, bromine, and iodine substituents in the p-position of phenyl rings were studied and compared. Their single-crystal structures were studied by geometrical analysis and theoretical calculation. The study reveals that different halogen bonds are formed with respect to different halogen atoms, such as C...F and X...X (bromine and iodine atoms) interactions, and molecular stacking modes would be affected by halogen bonds directly. Comparative studies of photophysical properties in dilute solution and solid state indicate that halogen substitutions would not affect the emission processes of diaryl oxalates in dilute solution; this is not the case for their solid state. This work has demonstrated that halogen bonds play an important role in regulating structures and photophysical properties of diaryl oxalates. [ABSTRACT FROM AUTHOR]

Fluorescent materials have many interesting applications, but it remains difficult to control the luminescence of organic materials and in particular to retain the same luminescence in solution and in the solid state, a property of interest for various imaging applications. In this work, the influence of inorganic-anions on the crystal structure and physical–chemical properties of a series organic salts L + Cl − ( 1 ), L + ClO 4 − ( 2 ), L + NO 3 − ·H 2 O ( 3 ), 2 L + SO 4 2− ·2H 2 O ( 4 ) ( L = 4-[(4H-1,2,4-triazol-4-ylimino)methyl]phenol) has been investigated. Single crystal X-ray analyzes revealed that salt 1 formed a linear structure connected by H⋯O interactions, while salts 2 – 4 all formed 2D network structures through O⋯O interactions. The protonated L + s adopt face-to-face slipped π-stacked arrangement in salts 1 and 3 , while display monomer arrangements in 2 and 4 , the latter can be attribute to the entrapment of heavy anions in the crystal lattices. Optical-properties measurements of these four salts have shown L + arrangements dependent on solid-state properties: salt 1 and 3 show broad emission bands ( λ 1 = 478 nm, λ 2 = 487 nm) with a red shift of about 60 nm relative to its fluorescence in solvents, while 2 and 4 are similar to each other, exhibiting sharp bands ( λ 3 = 453 nm, λ 2 = 433 nm) with the higher ϕ PL values ( ϕ PL1 = 0.08, ϕ PL1 = 0.15, ϕ PL1 = 0.06, ϕ PL1 = 0.14). These results demonstrated the significant influence of inorganic-anions on the organic salts and the optical properties of organic materials could be modulated by entrapping different anions in lattice. [ABSTRACT FROM AUTHOR]

Although synthetic efforts to prepare carboxylato-bridged tetranuclear iron(III) clusters have been well preformed, introducing of functional groups on the coordination ligands to tune the structural, spectroscopic and physical properties of the cluster remains unstudied. Using amino functionalized ligands bipy-NH 2 and O 2 CPh-NH 2 , we have prepared a new cluster 1 ([Fe 4 O 2 (O 2 CPh-NH 2 ) 7 (bipy-NH 2 ) 2 ]·HO 2 CPh-NH 2 ·(CH 3 CN) 3 ·C 2 H 5 OH·OH) via a new precise orientated strategy starting from iron(II) compound. The cluster was characterized by UV–Vis, IR and Mossbauer spectroscopy, X-ray crystallography, cyclic voltammetric and magnetic studies. Results have shown that the [Fe 4 (μ 3 -O) 2 ] 8+ core was disposed in a bent “butterfly” arrangement, and the adjacent cores were connected into 1-D chain via hydrogen-bonding contacts involving lattice OH − anion, HO 2 CPh-NH 2 and solvent molecules. This 1D chain exhibits strong antiferromagnetic interactions, and irreversible electron reduction of one iron(III) ion to iron(II) at EP.C = −1.77 V vs SCE. Remarkably, color change from reddish violet to bluish green have been observed for this cluster upon protonating the amino functional groups. [ABSTRACT FROM AUTHOR]

In the present study, the assembly of 6-aminonicotinic acid with inorganic acids (HBr, HNO 3 and H 3 PO 4 ) has been performed, which resulted in the molecular salts C 6 H 7 N 2 O 2 + ·Br − ( 1 ), C 6 H 7 N 2 O 2 + ·NO 3 − ( 2 ) and C 6 H 7 N 2 O 2 + ·H 2 PO 4 − ( 3 ), respectively. These three molecular salts have been characterized by single-crystal X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and UV–Vis absorption spectroscopy (UV). The results revealed that molecular salt 1 exhibits an infinite 1-D chain structure stabilized mainly by N–H⋯Br contacts, while 2 and 3 show a 2-D network and a 3-D stereoscopic framework, respectively, which are stabilized mainly by strong N–H⋯O hydrogen bonding contacts. Hirshfeld surface analysis demonstrated the presence of H⋯H, O–H⋯N, C–H⋯π and π⋯π intermolecular interactions. In addition, the UV–Vis spectra exhibit a slight blue-shift to a shorter wavelength, which suggests the clear influence of the inorganic anions. [ABSTRACT FROM AUTHOR]

Three diaryl oxalate derivatives, bis(4-chlorophenyl)oxalate, bis(2, 6-dichlorophenyl)oxalate and bis(2, 4, 6-trichlorophenyl)oxalate, have been synthesized and characterized via X-ray single crystal diffraction, differential scanning calorimetry, thermogravimetric analysis and infrared spectra, for the purpose of studying the influence of chlorine substitution on the crystal structures of diaryl oxalate. This work has demonstrated that, depending on the position and number, chlorine substitution will influence the molecular geometries and stacking modes of diaryl oxalate by tuning the types and numbers of intermolecular interactions. [ABSTRACT FROM AUTHOR]

The co-crystallization of a benzimidazole derivative ( 1, CHNO, 3-[[[2-[[(4-Cyanophenyl) amino]methyl]-1-methyl-1H-benzimidazol-5-yl]carbonyl]pyridin-2-ylamino]propionic acid ethyl ester), with fumaric acid (FA) and maleic acid (MA), has been performed. The FA and MA molecules, both are connected with two molecules of CHNO, giving birth to a three-components compound ( 1·0.5FA, CHNO) and a four-components compound ( 1·MA, CHNO). Single-crystal X-ray diffractions show that the three different planar moieties (4-cyanophenyl, benzimidazol, and pyridin-2-yl) in compound CHNO display ' cis-form' conformation ( a) in the crystal of 1, while exhibiting 'intermediate-state' conformation ( b) and ' trans-form' conformation ( c) in compounds 1·0.5FA and 1·MA, respectively. Hirshfeld surfaces analysis, DFT calculations, DSC measurements, IR and Raman spectroscopy were performed, which revealed that the thermal stability of the three conformations follows the order c > b > a. [ABSTRACT FROM AUTHOR]

Investigations of spin-crossover in an iron(II) tris(diimine) system, based on the ligands L 1 (4,5-dimethy-2-(pyridine-2-yl)imidazole) and L 2 (1-acetic ethyl-2-(pyridine-2-yl)-imidazole), have been presented in this paper. The methyl groups at adjacent sites to the donor atoms in the ligand L 1 generated the crossover situation for complexes Fe( L 1 ) 3 (ClO 4 − ) 2 ( 1 ), Fe( L 1 ) 3 (BF 4 − ) 2 ( 2 ), Fe( L 1 ) 3 (PF 6 − ) 2 ( 3 ) and Fe( L 1 ) 3 (SbF 6 − ) 2 ( 4 ), while the acetic ethyl group at the non-coordinating NH site of the ligand L 2 resulted in an increase in the ligand field and generated a low-spin (LS) state for the complex Fe( L 2 ) 3 (ClO 4 − ) 2 ( 5 ). Complexes 1 and 5 were structurally characterized by single-crystal X-ray diffraction at different spin-states, while the phase purity of complexes 2 – 4 was confirmed by PXRD. Raman, IR and UV–Vis absorption spectra and magnetic properties of 1 – 4 were obtained, which revealed the influence of different counter anions on the spin transition temperatures. The blue-shift of IR and Raman spectra, red-shift and decrease in molar absorptivity of UV–Vis absorption spectra all follow the sequence 1 < 3 < 2 < 4 . [ABSTRACT FROM AUTHOR]

Four new complexes, [Co(dmbpy) 2 (dca) 2 ]·CH 3 OH ( 1 ), [Ni(dmbpy) 2 (dca) 2 ]·CH 3 OH ( 2 ), [Zn(dmbpy) 2 (dca) 2 ]·( 3 ) and [Cu(dmbpy) 2 (OH) 2 ]·5H 2 O ( 4 ) (dca = dicyanamide), derived from 4,4′-dimethyl-2,2′-bipyridine (dmbpy) have been synthesized and characterized by elemental analysis, TGA and single-crystal X-ray diffraction. Crystal structures and Hirshfeld surfaces analysis revealed that the complexes 1 – 3 were mainly supported by O H ⋯ N, C H ⋯ N and π ⋯ π intermolecular interactions, and for complex 4 , the uncoordinated water molecules play a key role in the construction of the 3D stacking motif. UV spectrum measurements demonstrate that all of the complexes show typical metal to ligand charge transfer (MLCT) absorption bands between 301 and 306 nm. Moreover, after complexation, the absorption maximum bands about intraligand π → π* transitions similarly show slightly red shift compared to dmbpy ligand, consisting with the DFT calculations. [ABSTRACT FROM AUTHOR]

The compound {[Zn(μ-dicyanamide)(pyrazinamide)](pyrazinamide)} has been synthesized and further characterized by elemental analysis, single-crystal X-ray diffraction, and thermogravimetric analysis. Structural analysis revealed that the dicyanamide anion acted as bridging ligand in a μ-1,5 mode, resulting a polymeric 1-D chain structure. The pairwise N3-H3B···N1 and N9-H9B···N7, N3-H3A···O2 and N9-H9A···O1, N3-H3B···N7 and N9-H9B···N1 multiple hydrogen bonding interactions, impart enhanced stability to supramolecular structures. Hirshfeld surfaces and fingerprint plots were applied to arrive at the same conclusion, which is stabilised mainly by H-H, N-H, O-H interactions. DNA binding studies showed that the compound had interacted with DNA. [ABSTRACT FROM AUTHOR]

Investigation of spin-crossover in iron(II)-di(diamine) system, based on ligands L 1 , 4,5-dimethy-2-(pyridine-2-yl)imidazole, has been presented in this paper. The methyl group at the adjacent sites of the donor atoms in ligand L 1 can generate the crossover situation for the iron(II) tris(diimine) system. While for the iron(II)-di(diamine) system with L 1 , the results are complicated: complex 1 {Fe( L 1 ) 2 (SCN) 2 } displays paramagnetic behavior while 2 {Fe( L 1 ) 2 (SeCN) 2 } is in crossover situation. The difference was attributed to the various ligand field strength of SCN − and SeCN − , which also resulted to the blue-shift of IR and Raman spectra, as well as red-shift and decrease in molar absorptivity of UV–Vis absorption spectrum. [ABSTRACT FROM AUTHOR]

Two iso-structural two-dimensional (2D) porous coordination polymers, which formulated as [Fe(1,3-di(4-pyridyl)propane) 2 (NCX) 2 ] 2 (X = S [ 1 ], Se [ 2 ]) and featured 2-fold interpenetration, have been synthesised and characterized. Crystal structure, Hirshfeld surfaces analysis and magnetic properties of them were described. The basic-unit of 1 and 2 was the 2D rhombic grids [2 × (4, 4)] network, and the intermolecular interactions in the crystals were dominated by C–H…π, H–H and C–H…S (Se) contacts. The stronger ligand field strength of SeCN − than that of SCN − resulted to different magnetic properties: compound 1 shows paramagnetic property while 2 display displays an incomplete SCO transition approximately 30% conversion of high-spin (HS) to low-spin iron(II) sites with transition temperature of 100 K. [ABSTRACT FROM AUTHOR]